How to remove special characters from a string?

Suppose when a string consists of many special characters, we want to remove all special characters from it. My task is to purify my string by removing all special characters. For this purpose, I have developed a code, but it is not working properly. Here is the code below:

my_string = "Hello, world! How are you doing?"
new_string = my_string.replace('!', '')

The above code is replacing one special character at a time. My string contains more than one. Can someone help me with the code that removes all special characters in my string?